A rapid estimation method of structural fatigue analysis for a 17k ton DWT oil tanker

Abstract

Fatigue cracks and fatigue damage have been important issues for ships and offshore structures for a long time. However, in the last decade, with the introduction of higher tensile steel in hull structures and increasingly large ship dimensions, the greater attention should be paid to fatigue problems. Most research focuses on how to more easily access the fatigue strength of ships. Also, the major classification societies have already released their fatigue assessment notes. However, due to the complexity of factors influencing fatigue performances, such as wave load and pressure from cargo, the combination of different stress components, stress on concentration of local structure details, means stress, and the corrosive environments, there are different specifications with varying classification societies, leading to the different results from different fatigue assessment methods. This paper established the Det Norske Veritas(DNV) classification notes “fatigue assessment of ship structures” that explains the process of fatigue assessment and simplified methods. Finally, a fatigue analysis was performed by use data of a real ship and the reliability of the result was assessed.

Keywords

rapid estimation / structural fatigue analysis / reliability analysis / S-N curve / DNV fatigue assessment rules